TucsonJim wrote:
Typically, it is caused by one of two things:
1. The hose between the filler neck and the evap canister is plugged. You can pull the hose off of the evap canister and blow air through it. It should cause any debris to clear.
2. The evap canister is plugged. You can check it by blowing air into the evap canister from the discharge side. If no air flows out the inlet side, you need to replace the canister. One other method to try is to pull off the inlet hose on the evap canister and see if you can pump gas. If so, it is one of the two problems identified above. Do not leave it like this permanently or risk the wrath of tampering with your emission control devices.
There are other issues such as a misrouted filler neck hose or a blockage between the tank and the filler neck, but those are as frequent a problem as the evap system issues.
Trouble shooting video
Jim
Before model year 2005, Ford had things like a evap canister, but because of tightened emissions controls, in 2005, they are only allowed to 'leak' something like 20 grams of fuel every 24 hours, and the fuel system is 'tight' and no canisters are on modern cars.
THis is a new or nearly new motorhome, so probably the problem started at the RV factory.
My buddy's 1987 Ford motorhome had a similar problem, and I fixed it when on a trip from California to Bowling Green KY. We where able to get 15 - 20 gallons of gas into the 33 gallon tank before some fuel gets into the vent line, and plugs it with only about 2 ounces of fuel. By the time we drove 150 miles, the fuel escaped from the air vent line, and we where able to add another 15 gallons, or perhaps get the tank to 3/4 full sometimes.
I found that the fuel filler tube is 2" diameter and the vent line going from the tank to the filler tube near the sidewall of the RV was wrapped around filler line, making SURE that there would be a low point in the hose at some point. I crawled under the RV, pulled off the vent line, ran it straight from the tank to the sidewall connection (into the fuel filler neck) and cut off about 6" of length.
On the way home, we where able to get 25+ gallons of gas in each tank full, and when pulling into Kingman AZ, we where running on empty for miles, and put 33 gallons into the tank! Gas stations east of Kingman are much more expensive than Kingman, and we had an extra 5 gallons in a tank on the RV storage rack.
Anyway the RV owner wanted more fuel. So I installed a 16 gallon front tank that had been taken off another E-250 van. The brackets fit into the factory holes in the E-350 dually frame, and it bolted right up. We got a fuel filler from a E-350 bus in a junkyard, and that worked out well too.
Now he can run the factory tank dry, then run off the front tank, and put 37 gallons into the main tank. so he found out that we still had about 4 gallons when we pulled into Kingman.
Anyway I think you can crawl under the RV and look for the problem. Because it is 'new' I would call the manufacure, and arrange a place that you are visiting, and pull into the RV dealership along the way. Call ahead for an appointment in advance, as they sometimes are really busy, and do not take factory warranty work right away.
This is actually one of those situations where going back to the manufacture, and taking 3 days out of your travel plans might be more of a pain than just having the next garage fix it and you pay the $50 - $100 cost, then can fill your tank full each time, Priceless!
Fred.
Good luck,
Fred.
